react.js中state，dispatch，action，reducer之间的关系和作用是什么呢？

@connect(
    state => ({
        projectGroupInfo: state.pManageReducer.getProjectGroupInfoResult,
        updateProjectResult: state.pManageReducer.updateProjectResult,
        deleteProjectResult: state.pManageReducer.deleteProjectResult,
        createProjectResult: state.pManageReducer.createProjectResult,
        createProjectLoading:  state.pManageReducer.createProjectLoading,
        updateProjectLoading:  state.pManageReducer.updateProjectLoading,
        deleteProjectLoading:  state.pManageReducer.deleteProjectLoading,
        projectGroupInfoLoading: state.pManageReducer.projectGroupInfoLoading,
        delMrAsynTaskConfigResult:  state.pManageReducer.delMrAsynTaskConfigResult,
        pManageReducer:  state.pManageReducer,
    }),
    dispatch => ({
        getProjectGroupInfo: bindActionCreators(getProjectGroupInfo, dispatch),
        updateProject: bindActionCreators(updateProject, dispatch),
        deleteProject: bindActionCreators(deleteProject, dispatch),
    })
)

上面的pManageReducer是什么意思呢？

action文件
export function getProjectGroupAllMembers(projectGroupId) {
    const path = "/workspace/listProjectGroupMembers";
    return {
        type: 'listProjectGroupMembers',
        payload: {
            promise: api.get(path,{
                params: {
                    projectGroupId
                }
            })
        },
        namespace
    }
}